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    <p>The misconception you have is that a column is stored inside a PDF file as a column. That's simply not the case. A PDF viewer doesn't understand tables, columns, paragraphs, lines of text or words.</p> <p>PDF was created as a page description language and it's really good at reproducing a page exactly the same on many different devices. Because that is its goal, it doesn't care about structure and what you're referring to is all structure.</p> <p>The way text is drawn by PDF is really, really simple. The instructions on the page will be something like this:</p> <ul> <li>Set this font</li> <li>Go to this point on the page</li> <li>Render these characters.</li> <li>Go to this other point on the page</li> <li>Render some more characters.</li> </ul> <p>While it's possible to also store some structure information in a PDF together with these instructions, it usually isn't done and it was implemented in the PDF format as an afterthought anyway.</p> <p>When you look at the (pseudo) instructions above, it's easy to understand how tables are drawn. There will simply be instructions in the file to move to a certain position for one cell and draw the text. Then more instructions to move to another cell and draw that text.</p> <p>If you want to reverse the operation and extract structured information from a PDF page, you'll have to "re-invent" the structure information. This means things like figuring out which text is on the same baseline and might thus belong to the same line. Which text is close enough together on that baseline so that it might be words or columns... Etc...</p> <p>Not an easy task at all as you have figured out!</p>
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    1. USDavid van Driessche
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    1. COSome pdf generating products even seem to try to midlead text recognition software; I e.g. came across "tables" in which columns were separated by single space characters (which using the word spacing operator were stretched to match the gap) while the space between individual words in the same column was created by moving the text insertion position with explicit operators.
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    2. CO*grin* I'm not sure that's really misleading. I think in many cases the PDF specification simply is too complex for someone trying to finish a project on time. I wouldn't be surprised if they simply didn't understand what they were doing. I wrote a PDF text editor at some point (about fifteen years ago) and the algorithms you need would take things like what you say into account anyway. But there's an awful lot of guesswork and optimisation involved for sure...
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A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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